JP2009010156A - Pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern forming method by which patterns differing in width can be easily formed at the same time. <P>SOLUTION: The pattern forming method includes the steps of: forming a plurality of linear patterns on a film 1 to be processed; forming side wall films on respective side walls of the plurality of linear patterns; depositing a material film of a material having the same main element with the plurality of linear patterns on the film 1 to be processed and between the side wall films formed on the respective side walls of the plurality of linear patterns; etching the material film to form isolated films as linear patterns between the side wall films and also form a pattern larger in width than the linear patterns on the film 1 to be processed; and removing the side wall films after etching the material film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pattern forming method.

  A so-called sidewall transfer pattern forming method using a sidewall pattern formed on a side surface of a dummy pattern as a mask for etching an underlying region as a technique capable of forming a pattern lower than the resolution limit of lithography with the progress of miniaturization of a semiconductor device It has been known. For example, in Patent Document 1, after a first mask pattern is formed on a base region, a second mask having predetermined mask portions on the side surfaces of a plurality of dummy line patterns formed at a first pitch on the base region. A method for manufacturing a semiconductor device is described in which a pattern is formed and a dummy line pattern is removed to use a first mask pattern and a predetermined mask portion as a mask when etching a base region.

However, in the method of manufacturing a semiconductor device described in Patent Document 1, since a process of etching both ends of the second mask pattern formed on the side surface of the dummy line pattern is performed, a line pattern having a wide portion is simultaneously formed. It is difficult to form.
JP 2006-303022 A

  An object of the present invention is to provide a pattern forming method capable of easily simultaneously forming patterns having different widths.

  One embodiment of the present invention includes a step of forming a plurality of line-shaped patterns on a film to be processed, a step of forming a sidewall film on each side wall of the plurality of line-shaped patterns, Between the sidewall films formed on the sidewalls of the line-shaped pattern, a process of depositing a material film whose main element is the same material as the plurality of line-shaped patterns, and etching the material film to form a line between the sidewall films And forming a pattern wider than the line-shaped pattern on the film to be processed, and a step of removing the sidewall film after etching the material film.

  Another embodiment of the present invention includes a step of stacking a first organic film, a first inorganic film, and a first resist on a film to be processed, and the first resist having a predetermined shape on the first resist. Forming a pattern, sequentially transferring the first pattern to the first inorganic film and the first organic film, and forming a pattern of the first organic film on the film to be processed; A step of forming a second inorganic film on the side wall of the pattern of the first organic film formed thereon, and a pattern of the first organic film on which the second inorganic film is formed on the side wall. A step of filling an organic film and a main element with the same second organic film; a step of forming a second inorganic film and a third inorganic film of the same main element on the second organic film; Depositing a second resist on the inorganic film and forming a second pattern of a predetermined shape on the second resist; A step of sequentially transferred to a membrane and the second organic layer, after sequentially transferred a second pattern, a pattern forming method and a step of removing the second inorganic film and the third inorganic film.

  ADVANTAGE OF THE INVENTION According to this invention, the pattern formation method which can form simultaneously the pattern from which width differs easily can be provided.

[First Embodiment]
(Pattern formation method)
FIG. 1A is a top view of a first step of the pattern forming method according to the first embodiment of the present invention, and FIG. 1B is a longitudinal section of the first step along the line AA ′ in FIG. 1A. FIG.

  As shown in FIG. 1B, a silicon nitride film 2 is deposited by CVD (Chemical Vapor Deposition) on a film to be processed 1 formed of polysilicon doped with a predetermined impurity. Then, a carbon film 3 as a first material film containing carbon or a first organic film, an SOG (Spin On Glass) 4 as a first inorganic film, and a resist 5 as a first resist are formed in this order. It is laminated on the nitride film 2. As an example, the carbon film 3 is formed with a thickness of 500 nm, the SOG 4 is formed with a thickness of 80 nm, and the resist 5 is formed with a thickness of 200 nm. Here, the carbon film 3 is used to reduce exposure light that is reflected by the processed film 1 and the silicon nitride film 2 and reaches the resist 5 during processing by the lithography method described in the following steps. The main component is carbon (C) to be absorbed.

  In addition, you may form the to-be-processed film 1 from the material containing a silicon oxide or silicon nitride, for example. Further, the carbon film 3 may be deposited directly on the film to be processed 1 without using the silicon nitride film 2. In this case, the processing performed above the silicon nitride film 2 in each step described below is performed above the film to be processed 1. Further, the resist 5 may be deposited directly on the carbon film 3 without using the SOG 4.

  FIG. 2A is a top view of a second step following the first step of the pattern forming method according to the first embodiment of the present invention, and FIG. 2B is a plan view of FIG. 2A according to the first embodiment. It is a longitudinal cross-sectional view of the 2nd process in an AA 'line.

  In the second step, a pattern having a predetermined shape is formed on the resist 5 using a lithography method. Specifically, as shown in FIG. 2A, a plurality of line patterns arranged in parallel to each other are formed on the resist 5. The plurality of line-shaped patterns are combined with each other at the end of each line-shaped pattern to form a comb-shaped pattern. As a result, the SOG 4 is exposed except the region where the pattern of the resist 5 is formed.

  Here, the pattern formed of the resist 5 can be formed with a limit width that can be formed by a lithography method. As an example, the width a of the portion corresponding to the comb teeth (line pattern) of the comb pattern formed by the resist 5 is formed to be 45 nm, and another line pattern adjacent to the one line pattern is formed. The pitch b is 90 nm.

  FIG. 3A is a top view of a third step following the second step of the pattern forming method according to the first embodiment of the present invention, and FIG. 3B is a plan view of FIG. 3A according to the first embodiment. It is a longitudinal cross-sectional view of the 3rd process in an AA 'line.

In the third step, the SOG 4 is dry etched by RIE (Reactive Ion Etching) using a gas such as CHF ₃ using the pattern of the resist 5 as a mask. Thereby, a plurality of line-shaped patterns formed by the resist 5 are transferred to the SOG 4.

  FIG. 4A is a top view of a fourth step following the third step of the pattern forming method according to the first embodiment of the present invention, and FIG. 4B is a plan view of FIG. 4A according to the first embodiment. It is a longitudinal cross-sectional view of the 4th process in an AA 'line.

In the fourth step, the resist 5 is peeled off from the SOG 4 by plasma ashing using O ₂ or the like, and the carbon film 3 is dry etched using the SOG 4 as a mask. As a result, the carbon film 3 having the SOG 4 pattern transferred onto the silicon nitride film 2 is formed.

  FIG. 5A is a top view of a fifth step following the fourth step of the pattern forming method according to the first embodiment of the present invention, and FIG. 5B is a plan view of FIG. 5A according to the first embodiment. It is a longitudinal cross-sectional view of the 5th process in an AA 'line.

  In the fifth step, the side wall of the carbon film 3 is selectively side-etched using a slimming process to narrow the width of the carbon film 3. The carbon film 3 is processed into a pattern having a dimension smaller than the pattern dimension formed on the resist 5 and the SOG 4. As an example, the width of the carbon film 3 shown in the cross-sectional view along the line A-A ′ is processed to be approximately ½ of the width of the SOG 4.

Here, in the slimming process, the sidewall of the carbon film 3 is etched using an etchant having an etching rate for the carbon film 3 higher than that for the silicon nitride film 2. As an example, dry etching using a gas in which Cl, CF ₄ or the like is mixed with O ₂ is used in the slimming process according to the present embodiment. In addition, the width of the carbon film 3 processed in the slimming process is not limited to the above example, and it is only necessary that the width of the carbon film 3 is reduced after the slimming process than before the slimming process.

  Note that the pattern width of the resist 5 formed on the SOG 4 in the second step may be slimmed, and the slimmed pattern of the resist 5 may be used as a mask. That is, the width of the pattern of the resist 5 is slimmed to the width of the pattern formed from the carbon film 3 in the fifth step, and the slimmed pattern of the resist 5 is transferred to the SOG 4. Then, the slimming process performed in the fifth step may be omitted by transferring the SOG 4 pattern to the carbon film 3.

  FIG. 6A is a top view of a sixth step following the fifth step of the pattern forming method according to the first embodiment of the present invention, and FIG. 6B is a plan view of FIG. 6A according to the first embodiment. It is a longitudinal cross-sectional view of the 6th process in an AA 'line.

  In the sixth step, SOG 4 is selectively etched and removed by wet etching. For the wet etching, an etchant having an etching rate for the SOG 4 higher than that for the carbon film 3 and the silicon nitride film 2 is used. Thereby, on the silicon nitride film 2, a plurality of line-shaped patterns having a pattern size obtained by narrowing the pattern size formed in the resist 5 and the SOG 4 are formed.

  FIG. 7A is a top view of a seventh step following the sixth step of the pattern forming method according to the first embodiment of the present invention, and FIG. 7B is a plan view of FIG. 7A according to the first embodiment. It is a longitudinal cross-sectional view of the 7th process in an AA 'line.

  In the seventh step, first, a silicon oxide film 7 is uniformly deposited on the upper surface of the silicon nitride film 2 by CVD or the like. Specifically, a silicon oxide film 7 having a thickness that covers the pattern of the carbon film 3 formed on the silicon nitride film 2 is deposited on the upper surface of the silicon nitride film 2. Then, the silicon oxide film 7 is selectively anisotropically processed with respect to the silicon nitride film 2 and the carbon film 3 using dry etching such as RIE.

  Thereby, a sidewall film made of the silicon oxide film 7 as the second inorganic film is formed on the sidewalls of the plurality of line-shaped patterns formed from the carbon film 3. Note that the distance d between the silicon oxide films 7 formed on the sidewalls of the carbon film 3 having a plurality of line-shaped patterns is substantially equal to the width c of the carbon film 3 as the line-shaped pattern. In addition, the silicon oxide film 7 is processed.

  8A is a top view of an eighth step following the seventh step of the pattern forming method according to the first embodiment of the present invention, and FIG. 8B is a plan view of FIG. 8A according to the first embodiment. It is a longitudinal cross-sectional view of the 8th process in an AA 'line.

  In the eighth step, a material film or a film as a second organic film formed of a material having the same main element as the plurality of line-shaped patterns formed from the carbon film 3 on the upper surface of the silicon nitride film 2 Deposit uniformly. In the present embodiment, a carbon film 8 as a material film is uniformly deposited on the upper surface of the silicon nitride film 2. Then, the upper surface of the carbon film 8 deposited by CMP (Chemical Mechanical Polishing) or the like is planarized. In this case, the upper surface of the carbon film 8 is planarized until the pattern formed from the silicon oxide film 7 covered with the carbon film 8 and the pattern formed from the carbon film 3 are exposed on the surface. As a result, the carbon film 8 is formed on the silicon nitride film 2 and the carbon film 8 is also formed between the silicon oxide films 7 formed on the side walls of the plurality of line-shaped patterns made of the carbon film 3. The

  FIG. 9A is a top view of a ninth step following the eighth step of the pattern forming method according to the first embodiment of the present invention, and FIG. 9B is a plan view of FIG. 9A according to the first embodiment. It is a longitudinal cross-sectional view of the 9th process in a BB 'line.

  In the ninth step, first, a silicon oxide film 9 is deposited as a third inorganic film on the top surfaces of the carbon film 3, the silicon oxide film 7 and the carbon film 8 after the planarization. Further, a resist 10 as a second resist is applied to the upper surface of the deposited silicon oxide film 9. Then, using a lithography method, the resist 10 is processed into a pattern having a predetermined shape.

  In this case, the first pattern formed by the carbon film 3, that is, the pattern of the carbon film 3 shown in the cross section along the line AA ′ in FIG. Of the silicon oxide film 9 so that the isolation of the pattern of the carbon film 8 between the silicon oxide films 7 formed on the respective sidewalls and the formation of the second pattern having a width wider than the first pattern are performed. Above, a plurality of patterns of resist 10 are aligned.

  That is, a pattern is formed from the resist 10 that etches the end region that is formed from the carbon film 3 and joins each of the plurality of patterns having a line shape. At the same time, a pattern having a shape for isolating each of the carbon films 8 between the silicon oxide films 7 formed on the side walls of the plurality of line-shaped patterns made of the carbon film 3 is formed from the resist 10. Further, a pattern having a width wider than the pattern width of the carbon film 3 having a line pattern is formed from the resist 10.

  10A is a top view of a tenth step following the ninth step of the pattern forming method according to the first embodiment of the invention, and FIG. 10B is a plan view of FIG. 10A according to the first embodiment. It is a longitudinal cross-sectional view of the 10th process in a BB 'line.

In the tenth step, the silicon oxide film 9 is etched by RIE using CHF ₃ or the like, using the pattern of the resist 10 formed in the ninth step as a mask. Subsequently, the carbon film 8 is selectively etched with respect to the silicon oxide film 9 and the silicon nitride film 2 by RIE using O ₂ or the like. At this time, the resist 10 on the silicon oxide film 9 is also removed by etching. Thereby, the carbon film 8 is processed into a shape corresponding to the pattern of the resist 10.

  11A is a top view of an eleventh step following the tenth step of the pattern forming method according to the first embodiment of the present invention, and FIG. 11B is a plan view of FIG. 11A according to the first embodiment. It is a longitudinal cross-sectional view of the 11th process in the BB 'line.

  In the eleventh step, the silicon oxide film 9 and the silicon oxide film 7 are selectively etched with respect to the silicon nitride film 2, the carbon film 3, and the carbon film 8 by wet etching using an etchant such as dilute hydrofluoric acid. And remove. In this embodiment, since the silicon oxide film 9 and the silicon oxide film 7 are formed of the same material, both can be removed by one etching using dilute hydrofluoric acid. As a result, the width of the pattern formed using the resist 5 in the second step is narrowed, and the line-shaped pattern is formed by narrowing the pitch of the line-shaped pattern formed in the second step. Furthermore, simultaneously with these patterns, a pattern wider than these patterns is formed.

  As an example, a linear pattern having a width c of 22.5 nm formed from the carbon film 3 and a width d formed from the carbon film 8 are formed on the silicon nitride film 2 through the eleventh step. A 22.5 nm line-shaped pattern is formed. As an example, the pitch e between the line pattern formed from the carbon film 3 and the line pattern formed from the carbon film 8 is the line pattern formed using the resist 5 in the second step. The pitch b is ½ of the pitch b of 45 nm. Thereafter, the obtained pattern, that is, the pattern formed from the carbon film 3 and the carbon film 8 shown in FIG. 11A is sequentially transferred to the silicon nitride film 2 and the film to be processed 1 to form an electrode pattern made of, for example, polysilicon. Can be formed.

(Effect of embodiment)
According to the first embodiment, the pattern width is narrower than the pattern width that can be formed by the lithography method, the fine line pattern has a narrower pitch than the pitch that can be formed by the lithography method, and the width is thicker than the thin line pattern. A pattern can be easily formed.

  In addition, according to the first embodiment, a fine line pattern and a pattern having a width wider than the fine line pattern can be formed simultaneously, and can be directly formed on a film to be processed or a silicon nitride film as an underlayer. Since the number of lithography and etching operations can be reduced, it is possible to suppress the occurrence of a step in the film to be processed or the silicon nitride film as the base layer after the etching process.

  The processed film 1 may be formed on a semiconductor such as silicon. In this case, after the predetermined pattern formed in this embodiment is transferred to the film 1 to be processed, the pattern formed from the film 1 to be processed is caused to function as a mask used for processing the semiconductor under the film 1 to be processed. Also good.

[Second Embodiment]
FIG. 12A is a top view of the pattern forming method according to the second embodiment of the present invention, and FIG. 12B is a longitudinal cross-sectional view of the process along the line CC ′ of FIG. 12A according to the second embodiment. FIG.

  In the second embodiment, the carbon film 3 formed on the silicon nitride film 2 has a predetermined process in substantially the same process as the first embodiment except that the shape of the carbon film 3 is different from that of the first embodiment. Form a pattern. Therefore, the details of the steps that are substantially the same as those in the first embodiment are omitted.

  In the second embodiment, the forms shown in FIGS. 12A and 12B can be formed in the same manner as the first to eighth steps of the first embodiment. In other words, in the second embodiment, after the fin-like carbon film 3 is formed on the silicon nitride film 2, the silicon oxide film 7 is formed on the side wall of the formed fin-like carbon film 3. Then, a carbon film 8 is deposited in a region on the silicon nitride film 2 where the carbon film 3 is not formed. Subsequently, by planarizing the upper surface of the carbon film 8 by CMP, the form shown in FIGS. 12A and 12B can be formed.

  13A is a top view of a process following the process shown in FIGS. 12A and 12B of the pattern forming method according to the second embodiment of the present invention, and FIG. 13B is a plan view of FIG. 13A according to the second embodiment. It is a longitudinal cross-sectional view of the process in line CC ′.

  As shown in FIG. 13A, in this step, first, a silicon oxide film 9 is deposited on the entire surface of the carbon film 8 after being planarized by CMP. A pattern covering a predetermined region including the region of the carbon film 3 and the region of the carbon film 8 in the region sandwiched between the silicon oxide films 7 and a width wider than the width of the pattern of the carbon film 3 are formed. A pattern having the resist 10 is formed using a lithography method.

  14A is a top view of a process following the process shown in FIGS. 13A and 13B of the pattern forming method according to the second embodiment of the present invention, and FIG. 14B is a plan view of FIG. 14A according to the second embodiment. It is a longitudinal cross-sectional view of the process in line CC ′.

In this step, the silicon oxide film 9 is etched by RIE using CHF ₃ or the like using the pattern of the resist 10 as a mask. Subsequently, the carbon film 8 is selectively etched with respect to the silicon oxide film 9 and the silicon nitride film 2 by RIE using O ₂ or the like. At this time, the resist 10 on the silicon oxide film 9 is also removed by etching. Thereby, the carbon film 8 having a shape corresponding to the pattern of the resist 10 is obtained.

  15A is a top view of a process following the process shown in FIGS. 14A and 14B of the pattern forming method according to the second embodiment of the present invention, and FIG. 15B is a plan view of FIG. 15A according to the second embodiment. It is a longitudinal cross-sectional view of the process in line CC ′.

  In this step, the silicon oxide film 9 and the silicon oxide film 7 are selectively removed from the silicon nitride film 2 by wet etching using an etchant such as dilute hydrofluoric acid. Thus, the first fine line pattern formed from the carbon film 8 and the second fine line pattern formed from the carbon film 3 and having a shorter length than the first fine line pattern are alternately formed. Further, simultaneously with the first fine line pattern and the second fine line pattern, a pattern wider than the first fine line pattern and the second fine line pattern is formed. Thereafter, similarly to the first embodiment, the pattern formed from the carbon film 3 and the carbon film 8 shown in FIG. 15A is sequentially transferred to the silicon nitride film 2 and the film to be processed 1 as the underlying layer. . Also in the second embodiment, the same effect as in the first embodiment can be obtained.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

It is a top view of the 1st process of the pattern formation method concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the 1st process in the A-A 'line | wire of FIG. 1A which concerns on the 1st Embodiment of this invention. It is a top view of the 2nd process following the 1st process of the pattern formation method concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the 2nd process in the A-A 'line | wire of FIG. 2A which concerns on the 1st Embodiment of this invention. It is a top view of the 3rd process following the 2nd process of the pattern formation method concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the 3rd process in the A-A 'line | wire of FIG. 3A which concerns on the 1st Embodiment of this invention. It is a top view of the 4th process following the 3rd process of the pattern formation method concerning an embodiment of the invention. It is a longitudinal cross-sectional view of the 4th process in the A-A 'line | wire of FIG. 4A which concerns on the 1st Embodiment of this invention. It is a top view of the 5th process following the 4th process of the pattern formation method concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the 5th process in the A-A 'line | wire of FIG. 5A which concerns on the 1st Embodiment of this invention. It is a top view of the 6th process following the 5th process of the pattern formation method concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the 6th process in the A-A 'line of FIG. 6A which concerns on the 1st Embodiment of this invention. It is a top view which shows the 7th process following the 6th process of the pattern formation method which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 7th process in the A-A 'line | wire of FIG. 7A which concerns on the 1st Embodiment of this invention. It is a top view which shows the 8th process following the 7th process of the pattern formation method which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 8th process in the A-A 'line | wire of FIG. 8A which concerns on the 1st Embodiment of this invention. It is a top view which shows the 9th process following the 8th process of the pattern formation method which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 9th process in the B-B 'line of Drawing 9A concerning a 1st embodiment of the present invention. It is a top view which shows the 10th process following the 9th process of the pattern formation method which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 10th process in the B-B 'line of Drawing 10A concerning a 1st embodiment of the present invention. It is a top view which shows the 11th process following the 10th process of the pattern formation method which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the 11th process in the B-B 'line of FIG. 11A which concerns on the 1st Embodiment of this invention. It is a top view of the pattern formation method which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the process in the C-C 'line of FIG. 12A which concerns on the 2nd Embodiment of this invention. It is a top view of the process following the process shown to FIG. 12A and FIG. 12B of the pattern formation method which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the process in the C-C 'line of FIG. 13A which concerns on the 2nd Embodiment of this invention. It is a top view of the process following the process shown to FIG. 13A and FIG. 13B of the pattern formation method which concerns on the 2nd Embodiment of this invention. FIG. 14C is a longitudinal sectional view of a process taken along line C-C ′ of FIG. 14A according to the second embodiment of the present invention. It is a top view of the process following the process shown to FIG. 14A and FIG. 14B of the pattern formation method which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the process in the C-C 'line | wire of FIG. 15A which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1 Film to be processed 3, 8 Carbon film 4 SOG
5, 10 Resist 7, 9 Silicon oxide film

Claims (5)

Forming a plurality of line-shaped patterns on the film to be processed;
Forming a sidewall film on each sidewall of the plurality of line-shaped patterns;
Depositing a plurality of line-shaped patterns and a material film whose main element is the same material on the processed film and between the sidewall films formed on the sidewalls of the plurality of line-shaped patterns; ,
Etching the material film to isolate the sidewall film as a line pattern, and forming a pattern having a width wider than the line pattern on the film to be processed;
And a step of removing the sidewall film after etching the material film. The step of forming a plurality of line-shaped patterns includes:
Depositing a first material film on the workpiece film;
Forming a plurality of patterns on the first material film, each having a width wider than the plurality of line-shaped patterns by lithography,
The pattern forming method according to claim 1, further comprising: slimming the wide pattern formed on the first material film to form a plurality of the line-shaped patterns on the first material film. .   The pattern forming method according to claim 2, wherein the first material film includes carbon, and the sidewall film includes silicon oxide. Laminating a first organic film, a first inorganic film, and a first resist on the film to be processed;
Forming a first pattern of a predetermined shape on the first resist;
Sequentially transferring the first pattern to the first inorganic film and the first organic film to form a pattern of the first organic film on the film to be processed;
Forming a second inorganic film on a sidewall of the pattern of the first organic film formed on the film to be processed;
Filling the pattern of the first organic film in which the second inorganic film is formed on the sidewall with the second organic film having the same main element as the first organic film;
Forming a third inorganic film having the same main element as the second inorganic film on the second organic film;
Depositing a second resist on the third inorganic film and forming a second pattern of a predetermined shape on the second resist;
Sequentially transferring the second pattern to the third inorganic film and the second organic film;
And a step of removing the second inorganic film and the third inorganic film after sequentially transferring the second pattern.   The pattern forming method according to claim 4, wherein the first organic film and the second organic film contain carbon, and the second inorganic film and the third inorganic film contain silicon oxide.

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